As shown in FIGS. 1 and 2, the intravenous drip apparatus of the prior art comprises a solution dispensing device 11 of tubular construrction. The solution dispensing device 11 is provided at the top thereof with a connecting needle 12 piercing through the mouth 14 of a drip bottle 13. Attached to the bottom end of the solution dispensing device 11 is a solution transporting tube 15, which is connected with a hypodermic needle 16 for injecting intravenously a medical solution into a person's body. The solution dispensing device 11 is provided with a space for holding the medical solution to be injected intravenously into a person's body. Disposed at the midpoint of the solution transporting tube 15 is a control switch 17 for regulating the injection speed or shutting off the solution transporting tube 15. The mouth 14 of the drip bottle 13 is provided with an air needle 18 piercing therethrough for allowing the air to enter the drip bottle 13. In operation, the drip bottle 13 is so elevated as to permit the execution of an intravenous drip. Additional medical solution can be replenished in the midst of the intravenous drip by pulling the connecting needle 12 out of the drip bottle 13 and then by piercing the connecting needle 12 into another drip bottle filled with the fresh medical solution. However, such a replenishment of solution must be done in time to prevent the blood of a person receiving the intravenous drip to flow into the hypodermic needle 16 and the solution transporting tube 15. Such an incident often results in the clogging of the hypodermic needle 16 and the solution transporting tube 15 by the coagulated blood.
With a view to overcoming the shortcoming of the intravenous drip device of the prior art described above, the Taiwanese Patent Serial Number 81208567 (FIG. 3) discloses a solution dispensing device 21 which is provided therein horizontally with a partition 22 provided centrally with a hole 23, a stopping element 24, a body 25 of columnar construction and having two semi-circular heads 26 and 27. The body 25 is disposed in the hole 23 of the partition 22 such that the two heads 26 and 27 are located respectively on upper and lower sides of the partition 22. The body 25 and the lower head 27 are provided with a slot 28. When the solution dispensing device 21 contains the solution, the stopping element 24 is caused to rise so that the lower head 27 is stopped by the partition 22. As a result, the solution is allowed to flow through the partition 22 via the slot 28. As the process of intravenous drip is completed, the stopping element 24 is caused to descend so that the hole 23 of the partition 22 is obstructed by the upper head 26, thereby preventing the air from getting into the portion under the partition 22 so as to keep the solution level at the underside of the partition 22. In other words, the solution dispensing device 21 is therefore automatically shut off.
Another Taiwanese Patent Serial Number 81208778 (FIG. 4) discloses a solutiion dispensing device 31 which is provided with a floatable body 32 of spherical construction and having a thin ring 33. The floatable body 32 is caused to descend to obstruct the passage of the solution to the solution transpowering tube 34 at the time when the intravenous drip is completed.
The solution dispensing devices 21 and 31 described above are defective in design in that their automatic shut-off means do not work precisely in view of the fact that the devices 21 and 31 are made of a soft plastic material and are therefore vulnerable to deformation. For example, the deformation of the stopping element 24 or the floatable body 32 can bring about a complete failure of the automatic shut-off. In addition, the partition 22 is structurally complicated and can not be therefore made easily.